FIG. 5 shows a conventional LED lamp (see Patent Document 1 for example) in a sectional view. The LED lamp X illustrated in the figure includes an elongated rectangular substrate 91, a plurality of LEDs 92 mounted on the substrate 91, a tube 93 accommodating the substrate 91, and terminals 94. The substrate 91 is formed with a wiring pattern, not shown, connected to the LEDs 92 and the terminals 94. In the LED lamp X, the terminals 94 can be fitted into the inlet ports of a socket of a general-purpose fluorescent lighting fixture so that the LEDs 92 can be turned on.
The term general-purpose fluorescent lighting fixture refers to fluorescent lighting fixtures commonly used for interior lighting as the main application, and more specifically, lighting fixtures which use, for example in Japan, a commercial 100-volt or 200-volt power supply and to which a JIS C7617 straight-tube fluorescent lamp or a JIS C7618 circular fluorescent lamp can be attached.
However, since the LEDs 92 are spaced apart from each other in the LED lamp X, the light emitted from the LED lamp may not be uniform. Such non-uniformity can be corrected, for example, by increasing the wall thickness of the tube 94 thereby increasing light diffusion. In this case, however, the tube 94 has a decreased translucency, which poses another problem of decreased amount of light emission from the LED lamp X. Thus, the LED lamp X has not been an ideal substitute for a fluorescent lamp.
Patent Document 1: JP-U-6-54103